"Avastin is an anti-angiogenesis drug [one that inhibits blood supply to the tumor] that appears to have activity across a variety of cancers," Dr. Nancy Davidson, director of the breast cancer program at Johns Hopkins Kimmel Cancer Center in Baltimore and president of the American Society of Clinical Oncology (ASCO), said during a teleconference earlier this month.

"Angiogenesis is clearly a very important process in the tumorogenesis of many malignances, and one of the first agents we've had available to us in the clinic is Avastin, which has demonstrated some efficacy in several genotypes," said study author Dr. David Miles, a medical oncologist at the Mount Vernon Cancer Centre in Middlesex, U.K.

Miles, who is presenting the findings this weekend at the American Society for Clinical Oncology annual meeting in Chicago, spoke at a Saturday news conference.

The current study looked at Avastin added to the chemotherapy agent Taxotere (docetaxel). Taxotere is more commonly used outside the United States, while Taxol is more commonly used in the United States.

This phase III trial involved 736 patients randomized into one of three groups: Taxotere alone, Taxotere plus a high dose (15 mg/kg) of Avastin, or Taxotere plus a low dose of Avastin (7.5 mg/kg). The lower dose of Avastin is the current standard dose for breast cancer treatment, while the higher dose is the standard dose for colon cancer.

After a median follow-up of almost one year, women taking the lower dose of Avastin were 21 percent less likely and those taking the higher dose 28 percent less likely to have a recurrence compared to those receiving chemo alone. More than half (55.2 percent) in the low-dose group and two-thirds (63.3 percent) in the high-dose group saw their tumors shrink, compared to 44.4 percent in the placebo group.

Patients receiving Avastin did have more severe side effects (74 percent to 75 percent versus 67 percent in the chemotherapy-alone group).

Final data on overall survival is not yet available. According to Dr. Eric Weiner, director of the breast oncology center at Dana-Farber Cancer Institute in Boston and moderator of the Saturday news conference, "it is unlikely there will be a survival benefit."

The U.S. Food and Drug Administration tends to approve second and third-line drugs based on progression-free survival and drugs for the first-line setting on survival, Weiner said, adding that he "personally does not understand that approach."

Progression-free survival can be seen as a quality-of-life improvement. "Having the disease under control for longer, as long as the toxicity of treatment is not substantial, is something that is well worth it," Weiner said. "So a drug that can substantially improve profession-free survival is a drug that can at least, in some patients, make their lives that much better while they are dealing with this illness."